- Reactions of trifluoromethylpyridines with alkyllithium reagents. Directing effects of the trifluoromethyl groups
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Reactions of eight trifluoromethyl substituted pyridines with alkyllithium reagents were examined. 3-Trifluoromethylpyridine, 3,4-, and 3,5-bis(trifluoromethyl)pyridines undergo regioselective lithiation at the 2-position thus providing an easy access to 2-functionalised trifluoromethylpyridines. The reactions of 2-trifluoromethylpyridine, 2,4-, 2,6-bis(trifluoromethyl)-pyridines and 2,4,6-tris(trifluoromethyl)pyridine result exclusively by addition of RLi to the -N=C-bond. 2,5-Bis(trifluoromethylpyridine), depending on the reaction temperature, gives either 2-lithio derivative or an adduct.
- Porwisiak, Jacek,Dmowski, Wojciech
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- Recommendable routes to trifluoromethyl-substituted pyridine- and quinolinecarboxylic acids
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As part of a case study, rational strategies for the preparation of all ten 2-, 3-, or 4-pyridinecarboxylic acids and all nine 2-, 3-, 4-, or 8-quinolinecarboxylic acids bearing trifluoromethyl substituents at the 2-, 3-, or 4-position were elaborated. The trifluoromethyl group, if not already present in the precursor, was introduced either by the deoxygenative fluorination of suitable carboxylic acids with sulfur tetrafluoride or by the displacement of ring-bound bromine or iodine by trifluoromethylcopper generated in situ. The carboxy function was produced by treatment of organolithium or organomagnesium intermediates, products of halogen/metal or hydrogen/ metal permutation, with carbon dioxide. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Cottet, Fabrice,Marull, Marc,Lefebvre, Olivier,Schlosser, Manfred
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p. 1559 - 1568
(2007/10/03)
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